Debbie Gustafson of Dresher, Pennsylvania, was on the trip of a lifetime, touring the Galápagos with her family last March, when she began to feel the effects of COVID-19. Though her physical symptoms—diarrhea, dry cough, chills—were considered mild by doctors, her fatigue was crushing, and her mind was trapped in a fog. Once an avid reader, she couldn’t get through a page. “My eyes darted everywhere. I had no focus,” she told me. Before COVID-19, she’d held two part-time jobs, but she soon had to give up both of them.
The cognitive problems emerging from mild to moderate cases of COVID-19 are so new that researchers have struggled to define them. A just-published study led by Igor Koralnik, the director of the Neuro COVID-19 Clinic at Chicago’s Northwestern Memorial Hospital, analyzed the first 100 “long COVID” sufferers who came to the clinic, either in person or via virtual visits. None had ever been hospitalized for COVID-19, yet 85 percent had four or more neurological complaints, including “brain fog”—persistent trouble with focusing, retaining short-term memories, and managing complex tasks.
In February, the National Institutes of Health gave long COVID a clinical name: Post-Acute Sequelae of SARS-CoV-2 infection (PASC). But official recognition doesn’t tell us what percentage of COVID-19 sufferers experience lingering neurocognitive problems, or how many long-COVID patients there are. “There’s no numerator or denominator for the group yet,” says Sara Manning, a neurologist at the new Post-COVID Assessment and Recovery Clinic at the University of Pennsylvania, one of dozens of such clinics springing up in the United States and worldwide. That Koralnik’s study, like many of the new clinics, probably does not include many people without the resources or connections to find their way to specialized care only increases the uncertainty. “It’s likely there are many millions of these patients in the U.S., and dozens of millions in the world,” Koralnik told me. Like Gustafson, many of them are struggling with brain fog, and with its profound and often frightening disruptions to their daily lives. Now, in the second year of the pandemic, researchers and therapists are beginning to understand how to help them.